Many manufacturing processes require that various types of processing gases be supplied to the equipment used. The process gases are usually contained in high pressure cylinders and are provided to the equipment through a pressure regulator.
During production it is often required to isolate the process gas cylinder, the regulator and the process gas line from the equipment. This is necessary when the process gas cylinder or the pressure regulator must be changed. When this occurs the various lines must be vented and then purged with a purging gas, such as nitrogen. To do this various valves are often employed among the purging and process gas sources, pressure regulator, vents and equipment. However, with the multiplicity of valves, lines and components, there is a substantial opportunity for an operator to open or close the wrong valve at the wrong time. Such a mistake can expose the operator and others to toxic or highly flammable gases or contaminate a cylinder of expensive process gas.